1. Field of the Invention
This invention relates to photoelectric reflex optical systems, and, in particular, to coaxial reflected energy photoelectric scanners.
2. Description of the Prior Art
In reflex optical systems of the type described in U.S. Pat. No. 3,238,373, a photodetection device is located behind a light source. Under these circumstances, the amount of reflected energy absorbed by the photodetection device would be small in comparison to the total amount of reflected energy existing in such a system. Thus, the efficiency of this type of reflected photoelectric energy system is inherently very low.
In another type of reflex photoelectric scanning system described in reissue U.S. Pat. No. 26,915, a light source is placed at the focal point of a main lens, wherein a beam of collimated parallel light rays is generated out from the main lens. A photodetecting device and an auxiliary lens is positioned within this beam of light for detecting reflected energy. Inasmuch as the photodetection device and associated lens must be small in order not to obstruct the main portion of the light energy emanating from the main lens, the photodetection device and associated lens will be positioned to receive only a small amount of reflected energy from an object.